1. Field of the Invention
The invention relates to a base plate and particularly a plate for use in, production of concrete products.
2. Description of the Related Technology
As show in FIGS. 1 and 2, an empty base plate 20 taken from a plate storage 30 is introduced into a molding machine 10 during production of concrete products (composite blocks, plates, blocks, curbstones). The molding machine 10 includes a vertically movable mold 11, a press plunger 12 and a die plate 13. The base plate 20 is placed onto a vibrating table 14, which may be vibrated by an eccentric wheel or cam 15 or the like. Following the insertion of the base plate 20, the mold 11 is lowered onto: the plate 20 and filled from above with a mixture of cement and sand. The mixture is then densified by the pressure of the press plunger 12 lowered from above and the vibration of the table 14. Subsequently the press plunger 12 and the mold 11 are raised and the plate 20, with the molding, is pushed from the molding machine 10 onto conveyer rails 40. The plate 20 and the molding, are optionally moved by a stacking carriage 50 to a drying room 60 on. The molding is hardened in the drying room 60 conveyor rails 40. In a discharge station 70, the hardened molding is taken as a finished concrete product 80 from the base plate 20. The base plate is then returned to plate storage 30 for drying.
If the bate plates are equipped* on their bottom side, with stacking feet the base plates 20 may be stacked directly on rails in place Of a stacking carriage 50. In this case, the mutual distance of the stacking feet is sufficiently large so that when stacked a lower molding fits between the stacking feet of a plate 20 stacked above the lower molding. The bending rigidity of the base plate 20 must be high even when in extended storage and with the potential application of drying heat as the loaded base plate 20 rests on only two border areas on rails 40, the rails of the stacking carriage 40, the control rails of the drying room 80 or on stacking feet. If the base plate 20 is not entirely flat, hair cracks will develop during the hardening of the hardened concrete-sand mixture which render the finished concrete product useless.
Solid wood plates have been used heretofore to satisfy the aforementioned requirements of high base plate bending rigidity. The plates were assembled of individual planks, drawn together with steel reinforcing bars and protected on the frontal sides with metal profiles. As the wood, Spruce, larch or tropical hard woods have been used, with dimensions of 1400 mmxc3x97900 mmxc3x9750 mm, variable depending on the surface area required and on the strength of the wood used (hard or soft wood). Due to their assembly from individual planks, wooden, base plates have joints at the contact locations of the planks which interrupt the smoothness of the surface. Surface changes also occur over time due to the unavoidable abrasion and climatic effects on the wood. Furthermore, wooden base plates must be carefully maintained (regular oiling or spraying with impregnating agents and regular turning, so that both surfaces are used), in order to extend their useful life over a period of 2 to 5 years (depending on the type of wood).
The replacement of wooden materials by a plastic has, been heretofore unsuccessful because the plastics considered suitable for high loads would be significantly more expensive than wood. The increasing public criticism of the destruction of tropical rain forests further converts the use tropical hard woods into an environmental problem, which cannot be solved by the exclusive use of the spruce and larch wood, as soft woods may be used up to:certain loads only and they have less favorable production properties.
It is an object of the invention to create a base plate, which provides a permanent smooth surface requiring no maintenance even under very high loads, without being appreciably more expensive than conventional base plates,
This object is attained according to the invention by a base plate prepared from contaminated plastic wastes composed of between 70 and, got polyolefins by weight, between 0 and 15% polystyrene by weight, between 0 and 10% polyvinylchloride by weight and a residual proportion of other plastics and contaminants, plasticizing and extruded in the thermoplastic containing plastic components. Advantageously, the mixture contains at least polyolefins, polystyrene and polyvinylchloride.
The material may include fiber-containing material is added in a loose or continuous form. The fiber-containing material may be glass, wood, textile and/or plastic fibers. The fiber containing material may be added in the form of a fabric, a knit a mat. According to the invention, the edge zones of the body of the plate may exhibit embedded reinforcing pipes or rails. Alternatively, the plate may exhibit surface mounted reinforcing tails on the plate edges. The height of the reinforcing rails may be equal to or smaller than the height of the body of the plate. The reinforcing plates may have an essentially C shaped profile. Free ends of the C shaped profiles may include hook like projections cast into the body of the plate.
According to a further feature of the invention, stacking feet may be molded on the bottom side of the body of the plate, or on both the top and bottom side.
The base plate according to the invention may be produced from recycled plastic materials in a single piece and may optionally include molded stacking feet. Abutting joints and other changes in the flat surface, such as those found on wooden base plates, are eliminated. Furthermore, no maintenance is required and unlimited storage period are possible. The abrasion strength of the recycled plastics is considerably higher than that of wood, which altogether results in a significantly longer useful life than that of wooden materials. The utilization of plastic wastes as the raw material rather than tropical hard woods render the base plate of the invention especially friendly to the environment. The production costs of the base plate according to the invention are comparable with or even lower than those of wooden plates due to the use of plastic wastes as the initial material. The base plate according to the invention has been found highly suitable in view of the aforementioned advantages.